Among defects of conventional rulers, a user often encounters difficulties in drawing parallel lines of different scales due to insufficient scales provided and in preventing the ink from contaminating the working sheet.
Accordingly, this invention presents a rolling ruler to solve previous time- and labor-consuming problems. The present invention is based on the recognition that if the active edge of the ruler body can be slightly risen, the ink will no more contaminate the working sheet. Further, it would be extremely convenient if different scales may be selectively used without the necessity of changing the ruler body provided with the different scales.